The advent of radial keratotomy for correcting mild to moderate myopia (near-sightedness) has given rise to the need for a surgical instrument for effecting the operation in a well-controlled and reproducible manner. The operation essentially consists of making corneal incisions of desired depth and length for the purpose of changing intra-stromal corneal relationships in order to permanently flatten the cornea and reduce myopia and astigmatism. Currently, the incisions are made individually and consecutively by hand.
For example, the so-called Fyodorov method includes the marking of the center of the cornea and the desired incision lines with a wheel-spoke type solid template. The template is pressed onto the cornea to make an impression of the wheel-spoke configuration thereon, whereafter the surgeon will slice along each line with a surgical blade. The surgeon must oftentimes repeat the blade stroke and will occasionally and inadvertently perforate the cornea.
This conventional freehand method has a tendency to effect unequal and non-radial incisions. In addition, each new incision will decrease corneal rigidity so that subsequent incisions tend to be made deeper and not as straight as the prior ones. Another problem encountered with the above freehand method is one of the surgeon knowing when to begin and end a particular incision. If the incision should transverse the limbus, for example, undue bleeding and poor healing could result. Also, incisions of unequal length could create, rather than cure, astigmatism. Furthermore, such a freehand method is not conducive to making an incision across or subsequent to a previously-made incision since the latter incision will tend to gape.
The present invention is directed to overcoming one or more of the problems as set forth above.